Cold sintering of magnetic BaFe₁₂O₁₉ and other ferrites at 300 °C

Densifying ZnFe₂O₄ and BaFe₁₂O₁₉ at 300 °C to values greater than 90% of theoretical is demonstrated via hydroflux-assisted densification (HAD), a derivative of the cold sintering process employing non-aqueous, flux-based mass transport phases to facilitate particle consolidation. Previous attempts to cold sinter these materials with aqueous-based mass transport phases were not as successful with final densities < 90%. Attempts to densify NiFe₂O₄ and (Ni_0.5Zn_0.5)Fe₂O₄ only achieved densities around 80%, indicating an alternative transport phase may be needed to achieve high densities in Ni-containing materials. Magnetic hysteresis measurements of the low-temperature densified BaFe₁₂O₁₉ samples produced magnetic saturation values as high as 93 emu/g and coercive fields as high as 1789 Oe, which are comparable to values reported in the literature for this material produced via other processing techniques. Additional techniques are suggested to further optimize the magnetic properties of BaFe₁₂O₁₉ densified following the HAD approach.